PrimeGrid’s
Factorial Prime Search
On 14 Dec 2010, 02:12:42 UTC, PrimeGrid’s PRPNet found the largest known
Factorial prime:103040!-1
The prime is 471,794 digits long and enters Chris Caldwell's “The Largest Known
Primes Database” (http://primes.utm.edu/primes) ranked 1st for Factorial primes
and 136th overall.
The discovery was made by James Winskill of New Zealand using an Intel Core 2
Duo @ 2.13GHz with 2GB RAM, running 32 bit Windows XP. This computer took
about 46 hours and 42 minutes to complete the primality test using pfgw. Jamesis a member of the PrimeSearchTeam.
The prime was verified on 15 Dec 2010, by an Intel Q6600 @ 2.4 GHz with 2 GB
RAM, running 64 bit Windows XP Professional. This computer took a little over 20hours 56 minutes to complete the primality test using pfgw x64.
The credits for the discovery are as follows:
1. James Winskill (New Zealand), discoverer
2. PrimeGrid, et al.
3. fsieve/psieve/fpsieve, sieve programs developed by Mark Rodenkirch andGeoff Reynolds
4. PFGW, primality program developed by Chris Nash & Jim Fougeron
Entry in “The Largest Know Primes Database” can be found here:

http://primes.utm.edu/primes/page.php?id=96944
This is only the 25th known Factorial prime...the 15th discovery in the last 29 years.
It took 8 years to find the next factorial prime and now here’s another one just 2
months later.
Using a single PC would have taken years to find this prime. So this timely
discovery would not have been possible without the hundreds of volunteers who
contributed their spare CPU cycles. A special thanks to everyone who offered theiradvice and/or computing power to the search - especially Mark Rodenkirch andGeoff Reynolds who were major forces in moving the project forward. Also, thankyou to all the sievers and PRPNet’ers who contributed to this effort.
The Factorial Prime Search will continue to seek even larger primes. To join thesearch please visit PrimeGrid: http://www.primegrid.com

PrimeGrid’s
Factorial Prime Search
About PrimeGrid
PrimeGrid is a distributed computing project, developed by Rytis Slatkevičius, whichutilizes BOINC and PRPNet to search for primes. PrimeGrid's primary goal is to bringthe excitement of prime finding to the "everyday" computer user. Simply download
the software and let your computer do the rest. Participants can choose from avariety of prime forms to search. With a little patience, you may find a large oreven record breaking prime.
BOINCThe Berkeley Open Infrastructure for Network Computing (BOINC) is a
software platform for distributed computing using volunteered computerresources. It allows users to participate in multiple distributed computing
projects through a single program. Currently BOINC is being developed by ateam based at the University of California, Berkeley led by David Anderson.
This platform currently supports projects from biology to math to astronomy.
For more information, please visit BOINC: http://boinc.berkeley.edu
PRPNetPRPNet is a client/server application written by Mark Rodenkirch that is
specifically designed to help find prime numbers of various forms. It is easily
ported between various OS/hardware combinations. PRPNet does not run
each PRP test itself, but relies on helper programs, such as LLR, PFGW,
phrot, and genefer to do the work.
For more information, please visit PrimeGrid’s PRPNet forum thread:

http://www.primegrid.com/forum_thread.php?id=1215
For more information about PrimeGrid and a complete list of available prime search
projects, please visit: http://www.primegrid.com